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3D Printing: A New Mindset in Product Design

Friday, 01 March 2013

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What is 3D Printing?

The terms “3D printing” and “additive
manufacturing” refer to processes that
automatically build objects layer-by-layer
from computer data. The technology is
already well used in many sectors including
transportation, healthcare, military,
and education. Uses include buildingconcept
models, functional prototypes,
factory tooling (such as molds and robotarm
ends), and even finished goods
(such as aircraft internal components).
The aerospace and medical industries in
particular have developed advanced
applications for 3D printing. 3D printing
is sometimes referred to as “rapid prototyping,”
but this term does not encompass
all current uses for the technology.
Materials used in 3D printing include
resins, plastics, and, in some cases, metal.

The earliest method, stereolithography,
has been around since the late
1980s, but adoption was limited because
of the toxic chemicals it required and
the fragility of its models. Other technologies
have evolved since then, including
Fused Deposition Modeling
(FDM®). FDM, introduced in the early
1990s, lays down super-thin layers of production-
grade thermoplastic, yielding
comparatively durable models.

Since 3D printing’s inception, system
reliability and model quality have
increased, resulting in diverse applications.
At the same time, prices have gone
down to the point where some systems are
affordable even for small businesses. In a
2011 report, Wohlers Associates predicted
that worldwide annual sales of additive
manufacturing systems will reach 15,000
units by 2015 — more than double the
2010 rate. Lower-priced professional systems
will drive most of this growth.

In FDM Technology™, printer software
on the user’s Windows network or
workstation accepts computer-aided
design (CAD) data in major 3D file formats,
including .stl, .wrl, .ply, and .sfx
files. Some products also accept CT and
MRI diagnostic data, protein-modeling
data, and digitized 3D scans. The software
works like a paper printer’s driver,
sending data to the 3D printer as a job,
and telling the print head where to lay
down material.

Filaments of plastic modeling material
and soluble support material are heated
to a semi-liquid state, forced through an
extrusion tip, and precisely deposited in
extremely fine layers. (FDM layer thickness
ranges from 0.005 inch [.127 mm]
to 0.013 inch [.330 mm], depending on
the system.)

The print head moves in X-Y coordinates,
and the modeling base moves
down the Z axis as the model and its support
material are built from the bottom
up. The soluble support material (shown in brown in Figure 1) holds up overhanging
portions while the model is being
built, and allows for complex models —
even nested structures and multipart
assemblies with moving parts — to be 3D
printed. When the print job is complete,
the support material washes away and the
model is ready to be used or, if desired,
finished with paint or another process.

Some 3D printers are small enough
and clean enough to function as office
equipment inside a department or even
an individual cubicle. By comparison,
large rapid prototyping systems often
must be centrally located and run by a
dedicated staff of experts. The very
cheapest class of 3D printers comprises
home-use devices now on the market for
hobbyists. While fascinating for enthusiasts,
these machines differ from small
professional systems in that the resulting
models often have poor resolution, are
dimensionally inaccurate and unstable,
and lack durability.

Trends toward affordability and ease
of use are bringing professional 3D
printing technology in-house for many
designers and engineers. The growing
expectation that a CAD drawing can
become a real three-dimensional object
in a matter of hours is altering how companies
see the design process. It can be
faster, more effective, and less costly.

Using 3D Printing to
Accelerate Design

The longer a product stays in the
design cycle, the longer it takes to get to
market, meaning less potential profit for
the company. With increasing pressure
to get products to market quickly, companies
are compelled to make quick yet
accurate decisions during the conceptual
stage of design. These decisions can
affect the majority of total cost factors by
establishing material selection, manufacturing
techniques, and design longevity.
3D printing can optimize design processes
for greatest potential profit by speeding
iterations through product testing.

For example, Graco Inc. makes paint
spraying and texturing equipment for
professional use. Its engineers used a 3D
printer to experiment with various paint
gun and nozzle combinations to create
the perfect spray pattern and volume.
The resulting new spray-texture gun was
based on functional prototypes 3D printed
in ABS plastic. Graco estimates that
3D printing helped reduce development
time by as much as 75 percent.

Question of the Week

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